I don't like the new default either.
The thing is, I don't read all of the forums. I basically ignore politics and some of the others, and I have no interest in seeing all the new posts that have been made in those places. I'd like to be able to focus in on the forums of interest to me.
Another possible problem is that Sciforums wouldn't let me log on from a different computer away from home this afternoon. When I typed in my username and password, it welcomed me by name, and then told me that it was returning me to the page I had been on. So far, that's normal. But when I got there, I got the not-logged-in screen and couldn't post, even though 'Yazata' was now listed as online down at the bottom of the page. So I tried logging in again and the same thing happend, along with warnings about how I was using up log-in attempts. So apparently if I have Sciforums cookies on my home machine, it isn't going to allow me to post from any other machines. Not a big deal, but it annoyed me.